[EDITOR'S NOTE: Unfortunately, this is now gone. Your best bet for interisland flights is to use 10,000 miles roundtrip on Hawaiian via US Airways, United, Continental or Delta).
The days of the $38 interisland flights in Hawaii are long over ($150 is more like it now), so travelers planning trips in Hawaii may be once again thinking of using miles for flights between islands.
Most airlines charge 10,000 miles round trip for flights (though oddly, United charges 10,000 miles for a roundtrip ticket on Hawaiian Airlines, but Hawaiian charges 15,000 miles for the same flight).
However, Virgin Atlantic only charges 6,000 Flying Club miles for a roundtrip ticket on Hawaiian Airlines (9,000 in first class). I'll assume for a moment that you don't have any Flying Club miles. No worries: You have Starwood points? (You should, since you should be carrying the SPG Amex as your daily card because of its impressive array of transfer partners) You can transfer those Starwood points into Virgin Altantic Flying Club at a 1:1 ratio plus, of course, the 5,000 mile bonus for transferring 20,000 miles. Huge savings? No. But for a family of 4, you can get 4 tickets for the price of 2. Not too shabby.
Or (and thanks to IAH-PHX for pointing this out in the comments), you can use your Membership Rewards points to transfer into the Virgin Atlantic program.
(UPDATE: Even better news. Virgin Atlantic does not charge a fuel surcharge on Hawaiian. Inter-island tickets only require taxes of about $5.)